*FIXED* My Peavey 6505 is raising and dropping in volume

[Deleted member 10619]

Yeah I agree with you guys. I was just pissed off at the moment. Most of these costs are standard for a tube amp being maintained but still unwarranted on the very spot.

Anyway... got an update!

Got a very competent (and eccentric) local tech for the job (55 years of experience) and he is a close bud with Peavey’s head amp tech.

When I dropped the amp at his place and popped the chassis open, he told me a couple of very interesting things.

First of all, the foot switch contact was totally busted and he had to replace the part on the spot. It was adding noises and pops when he was engaging it with his test cables. But unrelated to the actual problem (it did drop some noise level down though).

As soon as the tech saw the board he started laughing (and cursing) at how and where the bias and choke mods were installed and gave me a bunch of reasonings why it was pretty iffy from his own perspective. To sum up all the rambling he gave me: “well, I guess it works but what in the hell was the tech thinking?”. So he said he’d clean the installation mess.

He told me to leave the amp for a couple of other tests. He then later called me back and told me that he figured out what the problem was on the board and that he’d show me in person by Monday when I pick it up.

So I’m glad it got fixed but I’m very disappointed that the amp was sold as “modded by a competent tech”, when in reality an actual competent tech is not approving in the least what was done on it and went as far as laughing at the apparent mess this tech did. It blew my mind that most of the present issues sound issues came from having someone tinker with its design.

I know it might be natural for some tech to shit on another tech’s job, but a full blown “what the HELL was this tech doing?” and laughing at an amateur job and showing me his mods as a side-by-side comparison (which looked super clean and less cluttered by comparison) is just an eye opener for me.

Yet again, I’m giving Mark the benefit of the doubt and say that the tech he worked with was amateurish and made a poor mod that only presented real problems after shipping it my way.

I’ll report back for exact news on what the real issue was, but its confirmed that the messy mod was the culprit.

 

[skullfxr]

I am glad that it worked out as well as it did - not ideal, but it COULD have been a lot worse.
...



I am going to say one thing unrelated to both parties, ask a lot of questions before you fork over the cash. Ask for pictures of mods, who did the mods, what is and is not included, last time blah was blah, etc. It makes the deal easier on both parties. Be a smart and informed buyer, be an informative seller. Make things clear. Hopefully somebody will read this and learn from the scenario.

 

[Deleted member 10619]

FINAL UPDATE

It is fixed!

The tech charged me $85. Not too bad.

So he summed up the problems being:

- Grounding issues
- Removing a ribbon cable that wasn't supposed to be there
- Footswitch contact replaced

The amp is no longer getting the volume fluctuation, the Peavey footswitch works perfectly and it is slightly quieter.

Thank you everyone who chimed in and gave me DIY suggestions!

 

[311boogieman]

Glad to hear it is finally all sorted. So the popping was tied to a grounding issue? What's up with the ribbon cable?

Most importantly though is......rock the fuck out of that bitch!

 

[maddnotez]

Yeah that is weird there was an extra part inside but hey whatever as long as it's working.

 

[iceguy154]

I have the EXACT same problem with used 6505+ that I got 5 years ago. Just started happening. I’m gonna have to see if someone did a half ass bias mod like yours cause NOTHING else I have tried has made a difference. Thanks for this info!!

 

[anomaly]

I'm having similar issues with my Mesa Mark IV. It makes a loud popping noise when i take it off standby and it has volume fluctuations. Tried new tubes. Didn't work...

 

[skoora]

The internet strikes again. Access to information, ie. Mods, tweaks but then carried out by lay people who aren’t truly qualified to go a good job. Suddenly we have all these amps that for years rocked, as is, now containing DIY mods that the internet said were so good you must try It. And how many people are going to document what they did and when selling clearly explain what they did? I remember when the 5150 mods were making the rounds. Make “X“ tighter with this, remove fizz with “Y” and even though it was interesting reading from a personal geek perspective, I found myself wondering why I would bother. I had a bias mod done to my Stiletto years ago, out of curiosity if anything and the change? Barely noticeable. It sounded great before so I don’t know what I was expecting exactly. I suppose it at least opened up using whatever EL34’s I wanted but the tone was not significantly more rockin’. But now I have an amp where the tech said don’t use the 50 watt mode now. I never did, so no biggie but the amp lost a feature for negligible gain. I used a stock 5150 in the 90’s and it was great and the tone on Heartwork is obviously shit. if only they had modded for a choke or less fizz...lol. I’ve really gone off mods on already established classics for tone reasons. Functionality reasons is always up for grabs..loops, second footswitchable masters etc. I feel there are so many amazing pedals now I just wouldn’t need to mod an amp.

 

[japetus]

The internet strikes again. Access to information, ie. Mods, tweaks but then carried out by lay people who aren’t truly qualified to go a good job. Suddenly we have all these amps that for years rocked, as is, now containing DIY mods that the internet said were so good you must try It. And how many people are going to document what they did and when selling clearly explain what they did? I remember when the 5150 mods were making the rounds. Make “X“ tighter with this, remove fizz with “Y” and even though it was interesting reading from a personal geek perspective, I found myself wondering why I would bother. I had a bias mod done to my Stiletto years ago, out of curiosity if anything and the change? Barely noticeable. It sounded great before so I don’t know what I was expecting exactly. I suppose it at least opened up using whatever EL34’s I wanted but the tone was not significantly more rockin’. But now I have an amp where the tech said don’t use the 50 watt mode now. I never did, so no biggie but the amp lost a feature for negligible gain. I used a stock 5150 in the 90’s and it was great and the tone on Heartwork is obviously shit. if only they had modded for a choke or less fizz...lol. I’ve really gone off mods on already established classics for tone reasons. Functionality reasons is always up for grabs..loops, second footswitchable masters etc. I feel there are so many amazing pedals now I just wouldn’t need to mod an amp.

I remember when EVERYONE was doing the bias mods to their 5150.

 

[iceguy154]

Can I tell if my 6505 has been BIAS MODDED using only the test ports on the back of the head and a multi meter? IIRC I have factory spec voltages at that test port, but i recall people saying the port was useless for some reason...
As far as the MOD goes, I am pretty unfamiliar as to why anyone would want to mess with the peavey design, but I know its pretty popular, and I wouldn't doubt that a previous owner tried it or had it done. Im not sure how to tell....Even if i open it the amp up, no idea what to look for.

As of now, my amp is behaving the same as OP's was. Glad to see that his got resolved but many others have similar complaints. I hope they are not different and unique issues altogether.....My understanding is that this is a pretty solid head in common use by many working musicians, and shouldnt be failing in this manner. Botched Bias mods by amateurs make the most sense here....